The core will handle all clinical, laboratory, and administrative needs of the Program participants. The clinical core functions as an entry route for patients to be diagnosed, evaluated, and classified for MG. A clinical data base will be maintained on all MG patients participating in the clinical/laboratory core. Tissue specimens obtained on these patients (blood and thymus) will be processed in the laboratory core. A portion of these specimens will constitute those human specimens that are required for Projects 1 and 3. Other laboratory studies will consist of a battery of immunologic parameters that will form an immunologic data base that can be correlated with clinical data and with information obtained from T and B cell studies (Projects 1 and 3). All clinical and laboratory data obtained in the core will be entered into a computerized data base for retrieval and analysis. All administrative requirements for the Project will be processed through the core secretary.